ORHS sinkhole: Soccer players could be back on field within 2 to 3 weeks

Thursday

Apr 25, 2013 at 7:58 PMApr 25, 2013 at 8:00 PM

Work is underway this week to fill a large sinkhole on the Oak Ridge High School soccer field and school officials are hoping soccer players could be playing on the field again in less than three weeks.

by Donna Smith/Staff

Work is underway this week to fill a large sinkhole on the Oak Ridge High School soccer field and school officials are hoping soccer players could be playing on the field again in less than three weeks.

Until then, the soccer team can play on Blankenship Field.

Blount Excavating is currently working to fix the sinkhole. A geotextile fabric has been installed and on Tuesday morning Blount Excavating was filling the bottom of the hole with three layers of rock — riprap, followed by two layers of smaller rocks. Then clay and topsoil was to be added, followed by sod, according to Allen Thacker, the school system’s supervisor of maintenance and operations.

Thacker told the Oak Ridge Board of Education at its Monday night meeting that he expects the sod to be put down Friday or Monday and if the sod takes root, he hopes the players will be back on the field in 10 to 14 days.

School Board members told Interim School Superintendent Robert Smallridge and Thacker to get together to determine the “best estimate” of what the total cost of dealing with this sinkhole will be and ask the Oak Ridge City Council to reimburse the school system. Board member Bob Eby said in the past the school system has had enough money in the budget for such unexpected projects, but Council has told the School Board to instead return to Council and ask for money to pay for emergency projects. Thacker said he’d have better estimates by this Friday.

The sinkhole saga began on April 8, Thacker said, when ORHS Athletics Director Mike Mullins called the system’s maintenance and operations department concerning a hole that had opened on the soccer field. During practice, a player had noticed a depression in the field and called the coach over. When the coach probed the depression with his foot, an “an 18-inch opening fell out with a cavern-like space, 360 degrees around the opening, reaching back roughly four to six feet,” Thacker stated in the written report to the School Board.

The area was secured for the evening and on April 9, maintenance workers cleared the sod and brought in a backhoe to explore the opening and figure out whether it was a sinkhole caused by groundwater, a void left in the field from debris used as fill during the ORHS construction project years ago, or a leak in the geothermal well field.

Maintenance employees removed 25 to 30 yards of dirt in trying to reach the hole’s bottom. When the backhole did all the digging it could do, they found a soft layer of mud that could be probed another three feet or more. The hole was then five feet across and the depth was six feet or more, Thacker stated.

On April 10, the heating-ventilation, air-conditioning water treatment service employees were contacted to verify that the geothermal loop wasn’t compromised and causing a water leakage. After confirming it wasn’t, GEOServices was contacted for advice and company employees came to do site inspection April 11, later determining it was a sinkhole. Drilling was done that day.

Test samples were analyzed and an April 18 report stated bedrock was found to be at a depth of nearly 12 feet with groundwater at eight feet and five feet of standing water was in the hole.

Blount Excavating was recommended because of the company’s experience with sinkholes and because it had been the subcontractor that did the main excavation work during the ORHS construction/renovation work. Because of the weather, Blount Excavating didn’t start the work until Monday. The company gave a “time and materials” quote of $38,600, according to Thacker’s report.

Board member Angi Agle asked whether the water could be coming from a city source, such a pipeline, that wasn’t closed off during the construction process at the high school years before. Thacker said the water had been tested and there is “no indication that this is anything but groundwater.”